EFFECT OF RARE EARTH OXIDES(CeO_2,La_2O_3)ON PROPERTIES OF Pd/Al_2O_3 CATALYSTS FOR REDUCTION OF NITROGEN OXIDES BY METHANE

摘要

We have established that the thermal stability of supported Pd/Al_2O_3 catalysts is increased after they are modified by rare earth oxides(La_2O_3,Ce_2O_3).We have observed the effect of thermal activation of an aluminopalladium catalyst modified by lanthanum oxide.This effect is apparent in the increase of the specific catalytic activity in the reaction of high-temperature reduction of nitrogen oxides by methane after heat treatment of the catalyst at 850 °C.We have used X-ray photoelectron spectroscopy(XPS)to show that the reason for the thermal activation effect is stabilization of palladium in the Pd~(1+)state.